Malaysia Airlines flight MH370, which disappeared after leaving Kuala Lumpur early on Saturday bound for Beijing with 239 people on board, may have turned back before vanishing, the country’s air force chief said yesterday, as intelligence agencies began an investigation into two passengers who boarded the Boeing 777 with stolen EU passports.

Speculation ranged from a mechanical fault that caused the aircraft to disintegrate mid-air to a possible terror attack that blew up the aircraft.

Despite repeated reports of objects and oil slicks in the sea, there was no conclusive trace of debris. Marine rescue teams worked through the night to search the sea south of Vietnam, while the aerial mission took place during daylight.

At least 40 ships and 22 aircraft from Vietnam, Malaysia, Thailand, Singapore, Indonesia, China and the United States are participating in the search. The airline warned families to prepare for the worst.

Military radar
Chief of Malaysia’s air force Rodzali Daud said radar indicated the aircraft may have turned back. “We are trying to make sense of this,” he Daud told a news conference. “The military radar indicated the aircraft may have made a turn back . . .”

In absence of any hard evidence, rumours abounded yesterday about what became of the aircraft, which vanished while flying in good weather at cruising altitude, losing contact with ground controllers between Malaysia and Vietnam. There was no distress signal.

The passengers were of 14 nationalities, including 152 Chinese plus one infant, 38 Malaysians, seven Indonesians, six Australians, five Indians, three French and three Americans, including one child.

Malaysia Airlines chief executive Ahmad Jauhari Yahya said pilots are supposed to inform the airline and traffic control if an aircraft does a U-turn. “From what we have, there was no such distress signal or distress call per se, so we are equally puzzled,” he said.

Authorities were checking on the identities of two passengers who boarded the aircraft with stolen passports in the names of Christian Kozel (30), from Austria, and Luigi Maraldi (37) from Italy.

Mystery passengers
On Saturday, the foreign ministries in Italy and Austria said the names of two citizens listed on the flight’s manifest matched the names on two passports reported stolen in Thailand during the past two years.

“I can confirm that we have the visuals of these two people on CCTV,” Malaysian transport minister Hishammuddin Hussein said. Interpol confirmed at least two stolen passports used by passengers were registered in its databases, but it said countries do not usually check for stolen passports.

However experts cautioned there were various reasons why people could have invalid documents.

The incident took place less than a week after 33 people were slashed to death in China by 10 knife-wielding assailants in a Kunming province train station in a co-ordinated terror attack, so speculation was rife.